function [x_Jh_sfoot_mat] = Jh_sfoot_mat(x)
x_Jh_sfoot_mat=[1.,0.,(-0.0508).*(cos(x(3)) + (-3.).*sin(x(3))),0.,0.,0.,0.,0., ...
  0.;0.,1.,(-0.0508).*(3..*cos(x(3)) + sin(x(3))),0.,0.,0.,0.,0.,0.; ...
  0.,0.,(-1.),0.,0.,0.,0.,0.,0.];
